1. Field of the Invention
The present invention relates generally to a sheet output device and to an image forming apparatus having a combination of a copying machine, a printer, a facsimile, or a combination of these devices and a sorter. The invention more particularly relates to a sheet output device and an image forming apparatus capable of transporting discharged sheets from a plurality of discharge bins to a large capacity stack.
2. Description of the Related Art
In the field of printers, sheet output devices having a plurality of discharge bins and a stack which can store a large number of paper sheets have been used. When a number of users share a printer having such a sheet output device, a discharge bin specific to each user is allocated and registered, and if a job sheet of a registered user is output, the job sheet is discharged onto the bin allocated to the user.
The capacity of sheets which can be stored in each discharge bin (bin capacity) is however limited, and if sheets continue to be output onto a particular discharge bin and the number of the output sheets reaches the storable bin capacity of the bin, sheets can be no longer output to that particular bin. As a result, if the number of output sheets to an discharge bin reaches the maximum storable capacity or if output job sheets are left behind for a prescribed time period at a discharge bin, the job sheets which have been output to the discharge bin are transported to the stack, so that sheets can be further output to the discharge bin.
In the conventional sheet output devices, however, a job sheet could be transported to a stack under a prescribed condition, even if the user (operator) lets the job sheet output to an discharge bin registered for the user. Therefore, when the user tries to take out the job sheet, he/she sometimes cannot be sure where a job sheet has been output, and might have to take time to look around all the discharge bins and the stack.